Isolation and maintenance of symbiotic fungi of ants in the tribe Attini (Hymenoptera: Formicidae)

Abstract

Neotropical Entomology 34(1): 001-005 (2005) Isolamento e Manutenção de Fungos Simbiontes de Formigas da Tribo Attini (Hymenoptera: Formicidae) RESUMO -O isolamento e a manutenção de fungos basidiomicetos simbiontes de formigas da tribo Attini tem sido dificultado pela baixa velocidade de crescimento desses fungos, bem como pela presença de muitos microrganismos que vivem na superfície do material que as formigas mantêm no interior nos ninhos como substrato para o crescimento dos seus fungos simbiontes. No presente trabalho nós descrevemos um método que aumenta em mais de sete vezes a eficiência de isolamento desses fungos, quando comparada àquela obtida por procedimentos tradicionais. Ninhos subterrâneos de formigas atíneas dos gêneros Atta, Acromyrmex, Trachymyrmex e Mycetarotes foram localizados e deles foram coletadas amostras contendo fungos simbiontes e formigas, que foram transportadas para o laboratório, onde as formigas foram capazes de limpar a cultura do fungo e estimular o seu crescimento. Em seguida, porções dos micélios foram assepticamente coletadas e transferidas para meio Yeast Nitrogen Base contendo glicose e cloranfenicol. Para facilitar a manutenção dos isolados em culturas de laboratório, diferentes nutrientes foram analisados para a elaboração de um meio de cultivo complexo, que possibilitou aumentar a velocidade de crescimento dos fungos e estocá-los por longos períodos. O método foi aplicado com sucesso para os fungos simbiontes de todos os gêneros de formigas estudados, gerando, assim, um procedimento extremamente útil para a formação e manutenção de uma coleção representativa de diferentes fungos simbiontes de formigas da tribo Attini. PALAVRAS-CHAVE: Atta, Acromyrmex, Trachymyrmex, Mycetarotes, basidiomiceto, simbiose ABSTRACT -The isolation and maintenance of symbiotic basidiomycete fungi living in association with ants of the tribe Attini has been hindered by the slow growth rate of these fungi and the presence of other microorganisms on the surface of the material which the ants maintain inside their nests to provide a growth substrate for their symbiont. In this paper we describe a method which increases the efficiency of isolation of these fungal symbionts by over seven fold as compared to traditional isolation procedures. Underground nests of attine ants of the genera Atta, Acromyrmex, Trachymyrmex and Mycetarotes were located, from which samples containing the fungal symbiont and ants were collected and transported to the laboratory where the ants were able to clean the fungal culture and stimulate its growth. As the symbiotic fungus grew, portions of its mycelium were collected and transferred to solid Yeast Nitrogen Base culture medium containing glucose and chloramphenicol. To facilitate the maintenance of the isolates in laboratory cultures, several nutrients were tested to formulate a complex culture medium for fast fungal growth and long-term storage. We successfully applied this methodology to the fungal symbionts of all the ant genera studied, thus producing a useful...

Leaf cutter ants (Atta cephalotes) harvest baits offering sodium chloride rewards

“…The leaf cutter's fungus garden could affect salt foraging by the ant workers. The symbiotic fungus requires sodium salts for growth (Silva-Pinhati et al, 2005). The ants can respond to changes in fungal condition by altering their foraging preferences, and the fungus can apparently signal its condition to the ants (North et al, 1999;Herz et al, 2008).…”

“…We used paper baits treated with aqueous solutions to test A. cephalotes willingness to harvest salt while foraging. We expected Atta foragers to harvest NaCl because both ants and their fungus require sodium at concentrations higher than typically found in green plant tissues (Silva-Pinhati et al, 2005;Kaspari et al, 2008).…”

Identification and variability of Monilinia spp. isolates from peach

“…For each isolate (Table 1), an 8 mm diameter disk containing the actively growing mycelium was individually deposited in the center of the Petri dish containing 15 mL plate -1 of the PDA  culture medium (40g of PDA and 1000 mL of distilled water), peach juice + agar (200 mL of peach juice, 3g of CaCO 3 , 15 g of agar and 800 mL of distilled water (Xiao & Sitton, 2004) and Pagnocca (10g glucose, 5g of NaCl, 5g of peptone, 10g of yeast extract, 17g of agar, 20g of hydrolyzed casein, 20g of soybean flakes, 20g of oat flakes and distilled water to obtain the final volume of 1000 mL) (Silva-Pinhati et al, 2005). The experimental design for the study of these variables was entirely randomized in a 3 x 35 factorial scheme (three culture media x 35 isolates), each plate being considered as a repetition, totaling six plates/isolate.…”

Comparison of radial growth rate of the mutualistic fungus of Atta sexdens rubropilosa forel in two culture media

“…Several authors have identified this microorganism as Leucoagaricus gongylophorus (=Leucocoprinus gongylophorus) based on the morphology of fruit-bodies which grow inside Atta sexdens rubropilosa (2) and Atta cephalotes (10) nests, or using molecular sequences (25). This fungus produces a special mycelia structure called gongylidia, rich in glycogen and used as food for the leafcutting larvae (1).…”